In a parts coating system, a conveyor chain from which trolleys are suspended is moved on rails. Works, such as automobile parts or electrical parts, to be coated with paint are suspended from the trolleys. Where works are relatively small and lightweight, the rail has a rectangular vertical cross section or a C-shaped cross section, for example. Where works are relatively large or heavy in weight, an I-shaped or H-shaped rail, for example, is used. A chain with rollers or a universal chain, for example, may be used as the conveyor chain. Where the trolleys must move in a curved path, a curved rail is used.
The rails (including curved rails), the chain and the trolleys thus comprise a single coating line or loop. Coating booths are located along the coating line. In each coating booth, paint of a particular color is provided (e.g., by spraying). Thus, if three coating booths are provided along the coating line, the coating line can coat three different kinds of parts with three different colors or can coat one part with three different colors. In actuality, however, chiefly because of a limitation of linear space, it is impossible or difficult to provide more than 3 or 4 coating booths along one coating line. Thus, if such a large number of coating booths must be used, it is necessary to provide an additional coating line or lines. And where more than one coating line is provided, each coating line is used for a coating with a particular color.
However, it is possible to reduce the necessary number of coating lines by employing a "flexible rail" of the invention which will be hereinafter described in detail. For example, if two coating lines are required to provide six coating booths in the prior art, the "flexible rail" of the invention can be used to reduce the number of coating lines to one while providing the same number of coating booths.